In recent years, a large size screen employing a plasma panel or a liquid crystal panel has been used in a television receiver featuring a thin body, and the large size and thin TV receivers have been well accepted in the market. This market trend requires that audio reproduction devices be downsized and thinner. At the same time, a home theater and the terrestrial digital broadcasting have prevailed in the market, and these media are capable of carrying quality sound. This market trend also requires that the audio reproduction devices reproduce quality sound and withstand greater maximum inputs.
One of the requests of reproducing the quality sound needs a reproduction technique of bass sound in order to reproduce dynamic sound incidental to cinemas. For instance, use of a passive radiator is one of the reproduction techniques of bass sound.
FIG. 7 shows a lateral sectional view of a conventional loudspeaker device having a passive radiator. Enclosure 1 has two openings 4a and 4b at its front, and loudspeaker unit 2 with magnetic circuit 2a is mounted to opening 4a. Passive radiator 3 is formed of flat diaphragm 3b and mounted to opening 4b via edge 3a supporting passive radiator 3.
In the conventional loudspeaker device discussed above, loudspeaker unit 2 produces exhaust pressure when it is driven, and this exhaust pressure is used for driving passive radiator 3. The drive of radiator 3 reinforces the reproduction of predetermined bass sound. This kind of conventional loudspeaker device is disclosed in, e.g. Unexamined Japanese Utility Model Publication No. S57-2790.
Diaphragm 3b and edge 3a are typically jointed with an adhesive, or by a molding resin. In the case of the molding resin, edge 3a is unitarily molded with diaphragm 3b through an outsert molding method. On the other hand, only diaphragm 3b is sometimes formed by cutting a board or through a molding process, and then diaphragm 3b is bonded to edge 3a. Since this bonding method needs no mold-die, it is advantageous cost-wise over the other method.
However, a stronger joint section between diaphragm 3b and edge 3a is required in the environment where larger and thinner video apparatuses as well as greater output from audio apparatuses are awaited.